Did cold cause Shippingport nuke reactor shutdown?

A frigid arctic air mass that brought record low temperatures to Pennsylvania, closing schools, courts and even some ski slopes is also being investigated as the possible cause of a nuclear reactor shutdown.

The dense mass of ultra-cold air began moving into the state on Monday afternoon, which is when one of two reactors shut down at FirstEnergy Corp.’s Beaver Valley Nuclear Power Station in Shippingport, about 25 miles northwest of Pittsburgh.

“There are many potential reasons this could happen and the cold weather is one of them,” FirstEnergy spokeswoman Jennifer Young said. “But there are hundreds of other causes we’re considering.”

The reactor shut down about 5 p.m. Monday when the National Weather Service said temperatures had fallen to about zero.

Nuclear Regulatory Commission spokesman Neil Sheehan called the shutdown “uneventful” and safe, but noted a fire suppression system was activated, dousing an electrical transformer with water. The transformer remained frozen Tuesday.

The transformer converts power created by the reactor to electrical voltage. The transformer’s failure prompted the reactor to shut down. The reactor remained shut Tuesday as an investigation into the cause continues, Young said.

The NRC has an inspector at the plant, who will oversee FirstEnergy’s investigation, any repairs and the reactor’s eventual return to service, Young said. That could take several days, if the transformer must be replaced, Sheehan said.